1. Field of the Invention
The present invention pertains to power management on a power bus, and, more particularly, to a Faraday electrical energy sink for a power bus.
2. Description of the Related Art
Electro-mechanical systems frequently generate power that is delivered to, for example, a motor over a power bus. The power bus has a nominal voltage at which the power source generates and delivers the power. However, it sometimes happens that one or more of the motor loads will generate power back onto the power bus in addition to that produced by the source.
For example, some aircraft use motors to operate flight control surfaces. A flight control surface such as a aileron or a rudder is rotated from a neutral position to effect a change in the heading of the aircraft. The power source generates a direct current (“DC”) power signal onto the bus that powers the motor. This power signal is delivered at the nominal voltage level of the power bus over which it is delivered. The flight control surface is then rotated back to its neutral position by the airflow across the flight control surface. Not only does this rotation not consume power off the power bus, but the rotation of the DC motor in the opposite direction generates additional power back onto the power bus. The actual voltage, or the actual measurable voltage (which may change with time), on the power bus momentarily exceeds the nominal voltage at this point.
The excess power needs to be managed to an “overvoltage” condition that may cause prevent damage to the apparatus. “Overvoltage” is a condition in which the actual voltage exceeds the maximum bus voltage, which is a specification-defined voltage value that the actual voltage should not exceed. Several techniques have been developed. For example, one approach simply dissipates the excess energy as heat in a resistive element. Another approach stores the energy in, for example, a capacitor bank, a flywheel, or a magnetic superconductor bank. Each of these management approaches possesses some drawback. Heat dissipation can lead to heat management problems in some applications and is inefficient. Capacitor banks require additional regulators to discharge the energy. Each of these factors may pose problems in some applications.
The present invention is directed to resolving, or at least reducing, one or all of the problems mentioned above.